Session: 03-20-02: Manufacturing: General

Paper Number: 144728

144728 - Experimental Study of Composite Prepreg Lay-Up and Fused Filament Fabricated Hydrodynamic Thrust Bearings 

Fixed geometry hydrodynamic thrust bearings are used in machinery with rotating shafts such as hydroelectric turbines, pumps, and marine propulsion systems. Dissimilar to traditional thrust bearings which are composed of races, a cage, and rolling elements, fixed geometry hydrodynamic thrust bearings only rely on a thin and pressurized lubricant film to reduce friction and transfer shaft thrust loads. A common type of fixed geometry hydrodynamic thrust bearing is the tapered-land thrust bearing; they are typically composed of a central lubricant inlet hole, lubricant veins to promote film generation, and sectors that have tapered and flat portions to stimulate pressurization of the lubricant film. During operation, a rotating shaft converges with the bearing, the lubricant is then drawn from the inlet hole and squeezed into the wedge-like region created by the tapered and flat sector geometry; this squeeze effect pressurizes the lubricant thus resisting axial loads and maintaining separation between the shaft and bearing. Performance metrics of tapered-land hydrodynamic thrust bearings include film pressure and thickness, as well as bearing temperature. During hydrodynamic bearing operation, the fluid film and bearing is heated due to frictional forces at the bearing and fluid interface. Mitigating friction and therefore bearing heating is important to prevent bearing wear and failure. Hydrodynamic thrust bearings are typically manufactured from metal-based stock materials. Some composite materials not only have comparable mechanical strengths and lower densities to metals, but can also have lower friction coefficients. One manufacturing method of composite based components is the manual or machine-controlled stacking of resin impregnated fibers or prepregs. Once a desired thickness is achieved, the composite component undergoes a curing process to harden the resin. In recent years, three-dimensional fused filament fabrication has emerged as another viable method for producing composite based components. Three-dimensional fused filament fabrication of composite components begins with a polymer filament that is impregnated with either continuous or chopped reinforcement fibers. The filament is directed through a heated nozzle and computer numerically controlled axis motors control where the heated filament is deposited onto a build plate; the component to be manufactured is constructed layer by layer until the final geometry is achieved. The research presented here aims to experimentally investigate the operating performance of composite hydrodynamic thrust bearings manufactured using prepreg layup and three-dimensional fused filament fabrication methods. Experimental analysis was conducted on a traditional aluminum based, bisphenol resin and carbon fiber prepreg layup, and a three-dimensional fused filament fabricated chopped carbon fiber filled nylon hydrodynamic tapered-land thrust bearing. Each bearing was subjected to loads and speeds ranging from 0.22 - 1.8 kN and 1500 - 6000 RPM, respectively. Film pressure distribution, film thickness and bearing temperature was recorded for each test. Spindle motor current was also recorded during each test so that frictional characteristics during bearing operation could also be analyzed. The data obtained in this analysis provides evidence that composite hydrodynamic thrust bearings manufactured using prepreg layup and three-dimensional fused filament fabrication can be used to reduce weight and operating temperatures of hydrodynamic thrust bearings.

Presenting Author: Muhammad Ali Ohio University

Presenting Author Biography: Dr. Ali is the Neil D. Thomas Professor and Graduate Chair in the Mechanical Engineering Department at Ohio University. He is also serving as the Director of the Center for Advanced Materials and Processing and affiliate faculty in Biomedical Engineering Program in Russ College of Engineering at Ohio University.

Authors:

Muhammad Ali Ohio University
Isaiah Yasko Ohio University